About Leeches: The history of medicinal use of leeches.
Australian Museum: Leeches: A study of the behavior, biology, adaptation to habitat, feeding habits and importance to medicine, reveals leeches to be fascinating and extraordinary animals.
Class Hirudinea: Basic introduction to the orders and families, habitat, and value as an indicator of overall ecosystem health.
Hirudinea: An introduction to the biology, classification and ecology of leeches, the subclass Hirudinae
Hirudo medicinalis: Article about the medicinal leech from Animal Diversity Web.
Leeches: Photographs of various species from the North Pacific and the Ukraine.
Leeches - Hirudinea: Photographs of members of representative taxa, and the equipment used in studying them.